1 /*
2 * src/test/examples/testlibpq2.c
3 *
4 *
5 * testlibpq2.c
6 * Test of the asynchronous notification interface
7 *
8 * Start this program, then from psql in another window do
9 * NOTIFY TBL2;
10 * Repeat four times to get this program to exit.
11 *
12 * Or, if you want to get fancy, try this:
13 * populate a database with the following commands
14 * (provided in src/test/examples/testlibpq2.sql):
15 *
16 * CREATE SCHEMA TESTLIBPQ2;
17 * SET search_path = TESTLIBPQ2;
18 * CREATE TABLE TBL1 (i int4);
19 * CREATE TABLE TBL2 (i int4);
20 * CREATE RULE r1 AS ON INSERT TO TBL1 DO
21 * (INSERT INTO TBL2 VALUES (new.i); NOTIFY TBL2);
22 *
23 * Start this program, then from psql do this four times:
24 *
25 * INSERT INTO TESTLIBPQ2.TBL1 VALUES (10);
26 */
27
28 #ifdef WIN32
29 #include <windows.h>
30 #endif
31 #include <stdio.h>
32 #include <stdlib.h>
33 #include <string.h>
34 #include <errno.h>
35 #include <sys/time.h>
36 #include <sys/types.h>
37 #ifdef HAVE_SYS_SELECT_H
38 #include <sys/select.h>
39 #endif
40
41 #include "libpq-fe.h"
42
43 static void
exit_nicely(PGconn * conn)44 exit_nicely(PGconn *conn)
45 {
46 PQfinish(conn);
47 exit(1);
48 }
49
50 int
main(int argc,char ** argv)51 main(int argc, char **argv)
52 {
53 const char *conninfo;
54 PGconn *conn;
55 PGresult *res;
56 PGnotify *notify;
57 int nnotifies;
58
59 /*
60 * If the user supplies a parameter on the command line, use it as the
61 * conninfo string; otherwise default to setting dbname=postgres and using
62 * environment variables or defaults for all other connection parameters.
63 */
64 if (argc > 1)
65 conninfo = argv[1];
66 else
67 conninfo = "dbname = postgres";
68
69 /* Make a connection to the database */
70 conn = PQconnectdb(conninfo);
71
72 /* Check to see that the backend connection was successfully made */
73 if (PQstatus(conn) != CONNECTION_OK)
74 {
75 fprintf(stderr, "Connection to database failed: %s",
76 PQerrorMessage(conn));
77 exit_nicely(conn);
78 }
79
80 /* Set always-secure search path, so malicous users can't take control. */
81 res = PQexec(conn,
82 "SELECT pg_catalog.set_config('search_path', '', false)");
83 if (PQresultStatus(res) != PGRES_TUPLES_OK)
84 {
85 fprintf(stderr, "SET failed: %s", PQerrorMessage(conn));
86 PQclear(res);
87 exit_nicely(conn);
88 }
89
90 /*
91 * Should PQclear PGresult whenever it is no longer needed to avoid memory
92 * leaks
93 */
94 PQclear(res);
95
96 /*
97 * Issue LISTEN command to enable notifications from the rule's NOTIFY.
98 */
99 res = PQexec(conn, "LISTEN TBL2");
100 if (PQresultStatus(res) != PGRES_COMMAND_OK)
101 {
102 fprintf(stderr, "LISTEN command failed: %s", PQerrorMessage(conn));
103 PQclear(res);
104 exit_nicely(conn);
105 }
106 PQclear(res);
107
108 /* Quit after four notifies are received. */
109 nnotifies = 0;
110 while (nnotifies < 4)
111 {
112 /*
113 * Sleep until something happens on the connection. We use select(2)
114 * to wait for input, but you could also use poll() or similar
115 * facilities.
116 */
117 int sock;
118 fd_set input_mask;
119
120 sock = PQsocket(conn);
121
122 if (sock < 0)
123 break; /* shouldn't happen */
124
125 FD_ZERO(&input_mask);
126 FD_SET(sock, &input_mask);
127
128 if (select(sock + 1, &input_mask, NULL, NULL, NULL) < 0)
129 {
130 fprintf(stderr, "select() failed: %s\n", strerror(errno));
131 exit_nicely(conn);
132 }
133
134 /* Now check for input */
135 PQconsumeInput(conn);
136 while ((notify = PQnotifies(conn)) != NULL)
137 {
138 fprintf(stderr,
139 "ASYNC NOTIFY of '%s' received from backend PID %d\n",
140 notify->relname, notify->be_pid);
141 PQfreemem(notify);
142 nnotifies++;
143 PQconsumeInput(conn);
144 }
145 }
146
147 fprintf(stderr, "Done.\n");
148
149 /* close the connection to the database and cleanup */
150 PQfinish(conn);
151
152 return 0;
153 }
154